Kinetic study of calcium carbonate precipitation in gas field brine containing methanol

Precipitation of calcite in pipelines and process vessels of petroleum industry may jeopardize flow assurance, and give rise to corrosion problems. In the present study growth rate of calcite crystals in gas-field brine under the influence of methanol used for hydrate prevention was experimentally investigated. Experimental results showed that calcite precipitated per unit mass of brine increased as the methanol concentration in the brine increased from 0 to 60 wt%. Different concentrations of methanol in brine are influential in mechanisms of growth, nucleation, and agglomeration of calcite. Kinetic parameters in rate equations of these mechanisms were calculated by model fitting to experimental data. Agreement of the model predictions with experimental results beyond the range at which the model parameters were adjusted indicated the validity of the model parameters. Results of this study may be used in petroleum industry to predict calcite crystallization at different concentrations of methanol in the gas-field brine in pipelines and process vessels.

► Effect of methanol on calcite precipitation from gas-field brine was investigated.
► The mass of calcite precipitate increases with methanol concentration of the brine.
► Kinetic parameters in the absence and in the presence of methanol were optimized.
► Methanol was influential in the value of nucleation rate coefficient.
► Growth and agglomeration mechanisms were not apparently influenced by methanol.